import java.util.Scanner;

public class Test {
    public static int Sum(int n){
        if(n<=1){
            return n;
        }else {
            return n+Sum(n-1);
        }
    }
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int sum=0;
        for(int i=1;i<=n;i++){
            sum+=Sum(i);
        }
        System.out.println(sum);
    }
    public static int max(int a,int b){
        return a>b?a:b;
    }
    public static double max(double a,double b,double c){
        double max=a;
        if(max<b){
            max=b;
        }
        return max>c?max:c;
    }
    public static void main6(String[] args){
        Scanner sc=new Scanner(System.in);
        int a=sc.nextInt();
        int b=sc.nextInt();
        double x=sc.nextDouble();
        double y=sc.nextDouble();
        double z=sc.nextDouble();
        System.out.println(max(a,b));
        System.out.println(max(x,y,z));
    }
    public static int sum(int a,int b){
        return a+b;
    }
    public static double sum(double a,double b,double c){
        return a+b+c;
    }
    public static void main5(String[] args){
        Scanner sc=new Scanner(System.in);
        int a=sc.nextInt();
        int b=sc.nextInt();
        double x=sc.nextDouble();
        double y=sc.nextDouble();
        double z=sc.nextDouble();
        System.out.println(sum(a,b));
        System.out.println(sum(x,y,z));
    }
    public static int fab(int n){
        if(n<=1)
            return n;
        else{
            return fab(n-1)+fab(n-2);
        }
    }
    public static void main4(String[] args){
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        for(int i=0;i<=n;i++){
            System.out.print(fab(i)+" ");
        }
    }
    public static void main3(String[] args){
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        int sum=0;
        for(int i=1;i<=n;i++){
            sum+=fac(i);
        }
        System.out.println(sum);
    }
    public static int fac(int n){
        if(n<=1) {
            return 1;
        }
        else {
            return n*fac(n-1);
        }
    }
    public static void main2(String[] args){
        Scanner sc=new Scanner(System.in);
        int n=sc.nextInt();
        System.out.println(fac(n));
    }
    public static int max2(int a,int b){
        return a>b?a:b;
    }
    public static int max3(int a,int b,int c){
        int ret=max2(a,b);
        return max2(ret,c);
    }
    public static void main1(String[] args){
        Scanner sc=new Scanner(System.in);
        int a=sc.nextInt();
        int b=sc.nextInt();
        int c=sc.nextInt();
        System.out.println(max2(a,b));
        System.out.println(max3(a,b,c));
    }
}
